package nowCoder;

import java.util.Scanner;

/**
 * @Auther: zzx
 * @Date: 2024.03.24/3/6
 */
public class HJ107 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double x = sc.nextDouble();
        double min = Math.min(-1,x);
        double max = Math.max(1,x);
        while (true){
            double temp = (min + max) / 2;
            if (temp * temp * temp > x){
                max = temp;
            }else {
                min = temp;
            }
            int i = (int) (min * 100);
            int i1 = (int) (max * 100);
            if (i == i1){
                System.out.printf("%.1f%n",(min + max) / 2);
                return;
            }
        }
    }
}
